Positron emission tomography (PET) is a functional imaging technique widely used in nuclear medicine and pre-clinical research, which produces a static or dynamic three-dimensional image or parameters of functional biological processes in live bodies. It can be used in cancer detection, staging and restaging, treatment planning and monitoring, as well as drug development. During a PET scan, a patient is introduced with positron-emitting radionuclide, which produces pairs of photons, the PET system then detects the photons and reconstructs the three-dimensional images or parameters showing the biological process inside the patient body.
To build a PET system, detector modules are developed to detect the photon pairs, which usually include high-density scintillator with photodetectors or directly gamma ray detectors to detect each individual photon with precise location, energy and time information, as well as with high efficiency. All detected events are sent to a centralized coincidence processing unit or distributed processing units, or software to sort out the prompt coincident events and/or the random coincident events.
The detector module may include power, clock, synchronization, and communication sections to work together but they are separately built. Conventionally, there are four different kinds of connectors and each kind is responsible for only one function.
Due to limited scan time, injection dose and the demand of high image quality, various methods are proposed to increase the system sensitivity. High-density detector or multiple detectors can improve the system sensitivity, and to further improve the image quality.
Recently, “Time of Flight” (TOF) is introduced and proven to improve the imaging quality and/or reduce injection dose and/or scan time. Without TOF, each detected event is back projected along a line (called line of response or LOR) within the range of object being imaged. With TOF, this range can be reduced by locating the event within the distance traveled, which is half of the product of the TOF and speed of light. For a non-TOF system, the required timing resolution is be typically below 5 nanoseconds, while a TOF system needs the timing resolution to be typically below 1 nanosecond, which requires the clock alignment (along with sync) to be below 1 nanosecond, or even less, such as around hundreds of picoseconds, as described in “Update on time-of-flight PET imaging” by Suleman Surti published on Journal of Nuclear Medicine. To achieve good timing or TOF, a precision clock and synchronization is needed in addition to the power and communication. However, these four components are still separately built, which causes inconveniences to the users.
There is a need for an integrated interface for the detector module including all components in a cost effective way. A unified integrated interface can be used to simplify the module design and the coincidence processing unit or uplink.